Insulin-dependent diabetes mellitus (IDDM) is mediated by a T lymphocyte- dependent autoimmune destruction of pancreatic b-cells. Although insulin therapy has increased the lifespan of type I diabetic patients, it has failed to influence the long-term complications of diabetes. The basis of these long-term complications is due to the failure of exogenous insulin therapy to achieve fine specificity of normal glucose homeostasis. The recent results of the DCCT that improved glycemic control reduces the progression of secondary complications of IDDM has provided impetus for the design of protocols to achieve euglycemia. In the recent past, much effort has been focused on identifying the autoantigens implicated in IDDM, with an ultimate goal of using them for immune intervention strategies to prevent IDDM during the preclinical stages. This method of study, although meritorious, does little to aid those patients already afflicted with established diabetes. For these patients, islet cell transplantation remains the most practical and most specific treatment to restore normoglycemia and thus, prevent the development of long-term complications of IDDM. A major drawback of the widespread application of islet transplantation for the treatment of diabetes has been the vulnerability of islet allografts to immunologic rejection. Recent advances in gene therapy provide hope for the molecular engineering of islets to promote donor- specific unresponsiveness. Both adenoviral and adenoassociated viral- mediated gene transfer offer the novel opportunity of transducing somatic, non-replicating cells with desirable genes. The overall objective of this project is to induce islet allograft tolerance. We propose to employ several well-characterized chemokines (i.e., uteroglobin, CTLA4Ig, vIL10, and TGFb1), utilizing the latest technologies of gene therapy to express these secretory immunomodulatory proteins within the islet cell allograft. These secretory cytokines have the capacity to immunomodulate the intraislet milieu and block several critical steps of the T cell activation cascade important in islet- directed alloimmune responses. Through the technique of islet-directed DNA virus-mediated gene therapy, we will introduce a "multiple hit" concept of local immunomodulation to promote islet allograft tolerance.